The present invention relates to improvements in heat exchangers of the regenerator type. In one aspect the invention relates to an improved thermal regenerator. In another aspect the invention relates to a method for constructing a thermal regenerator matrix.
A thermal regenerator is a combined thermal energy storage/supply convective heat transfer device which aids in establishing and maintaining a temperature difference in a working fluid between two regions in a thermodynamics machine. In a thermal regenerator, a solid material, hereinafter referred to as a matrix, is successively subjected to the influence of fluids at different temperatures, absorbing heat from a hotter fluid and subsequently imparting heat to a cooler fluid. Design of the thermal storage matrix is critical to the operation of a regenerator.
The desirable features of a thermal storage matrix include the following:
1. Large surface area per unit volume. PA1 2. High thermal energy storage capacity per unit volume. PA1 3. Low thermal conductivity in the direction of fluid flow. PA1 4. Low fluid space (void space) per unit volume. PA1 5. Low pressure drop per unit heat transfer. PA1 6. Physically stable; chemically inert. PA1 A. Small, closely packed sphere matrix, generally one diameter. PA1 B. Wire screen matrix, generally randomly stacked. PA1 C. "Corrugated" ceramic core, as described by Cohen, U.S. Pat. No. 2,552,937. PA1 D. Reticulated open cell ceramic foam. PA1 (a) Providing a composite woven structure consisting of a plurality of parallel, longitudinally oriented, spaced apart thermal members for storage and transfer of heat, a plurality of parallel, transversely oriented, spaced apart spacing members woven through the thermal members, and removable means for maintaining the thermal members in parallel relation; PA1 (b) Winding the composite structure spirally around a cylindrical mandrel to provide a wound matrix structure; PA1 (c) Disposing the wound structure in a regenerator housing comprising an outer wall, a central cylindrical core having closed ends, a first end closure means, a second end closure means, a first fluid transfer means in operable communication with the first end closure means and a second fluid transfer means in operable communication with the second end closure means, whereby a fluid may be transferred from one of the fluid transfer means through the matrix disposed in the housing to the other of the fluid transfer means; and, PA1 (d) removing the maintaining means.
Media selected for the thermal storage matrix have included the following:
Media A and B possess features 1, 2 and 3; however, they exhibit high pressure drop per unit heat transfer. Media C and D possess features 1, 2 and 5; however, they do not have features 3 and 4. What is desired is a matrix media having all the features described above.
It is an object of the present invention to provide a method for fabricating an improved thermal regenerator matrix.
It is another object of the present invention to provide an improved thermal regenerator.
Other objects, advantages and aspects of the present invention will be apparent to those skilled in the art.